1. Field of Invention
The present invention pertains to a vehicle suspension device, especially, a vehicular torsion bar suspension device.
2. Description of Related Arts
Nowadays, there are two types of suspension system. One is non-independent suspension; the other is independent suspension. The axle of the independent suspension is divided into two sections. Each wheel is independently mounted through a spiral spring under the vehicle frame; as a result, when bumping happens to one wheel, the other wheel will not be affected, and thereby the vibrations of the vehicle body will be reduced drastically and accordingly improve the comfortability effectively; especially, when driving in a highway, the running stability will be increase as well. However, this type of suspension structure has complicated structure, little carrying ability; and correspondingly, it makes the drive system and steering system of the vehicle get more complicated. Thus, current sedans have adopted the independent suspension system and have become a development trend.
The independent suspension has varieties of structures, such as sliding pillar type, MacPherson type, link type and etc. There are three types of metallic springs among these independent suspensions; they are spiral spring, leaf spring and torsion bar spring. The spiral spring got the name from its spiral line, and has advantages of light weight and small volume; when the shock force resulting from the road surface acts on the wheels, the spiral spring will be distorted and absorb the kinetic energy of the wheels and convert it into the potential energy of the spiral spring; accordingly the impact of the shock from road surface on the vehicle body will be decreased. The middle part of the leaf spring is fixed through a U-shape bolt to the axle; the spring eyes at two ends are hinged to the bracket of the vehicle frame through a peg; in this way, the axle and vehicle body are connected through the leaf spring; as a result, when the shock force resulting from the road surface acts on wheels, the leaf plate will be distorted and therefore bring the effect of buffering and shock absorption. The torsion bar spring has one end fixedly connected with the vehicle frame and the other end connected with the control arm of the suspension in order to fulfill the shock absorption by virtue of the torsion distortion of the torsion bar. Seen from the transverse section, the torsion bar spring has the circular type, tubular type, rectangular type, stacked type, combined type and etc. The circular torsion bar is applied the most. It takes on the shape of a rod, with two ends being able to be processed into the shape of spline, hexagon and etc., so as to fix one end to the vehicle frame and the other end to the wheels through the control arm. The torsion bar is made of alloy spring steel, which has very good elasticity and is subject to distortion and restoring; actually, it plays the same role as the spiral spring but with different form. When the vehicle is running, the wheels will jolt up and down due to the uneven road, and the control arm will also move up and down accordingly. When the wheels jolts up, the control arm moves up, so that the torsion bar is forced to distort and meanwhile absorb the shock energy. When the shock force gets less, the natural restoring capability of the bar is able to restore rapidly to its original position, and in turn makes wheels back to on the ground, preventing the vehicle from bumping.
Because the torsion bar spring bears only sheering force, a coil spring with the same weight can absorb more than double energy of a leaf plate with the same weight. The torsion bar spring is applied in automobiles in two ways; one is the longitudinal device and the other is the transverse device, the latter being used more often. In the longitudinal device, the torsion bar is used to substitute for the leaf spring and coil spring, which take up more rooms; for example, in the front suspension of vehicle type, Toyota Hiace, Zace, Surf, the torsion bar spring is used to match the A arm type of suspension system. The torsion bar of a transverse device is used to balance the acted force of the left and right wheels and as a balancing bar of anti-tilting, with the exception of fewer vehicle types that use the torsion bar to substitute for the coil spring.
In current auto suspension devices, the torsion bar spring is usually installed on the front suspension device of an automobile. Its front and rear elastic components are independent of each other in between, without any influence and connection. Even if the vibration direction of the front and rear wheels of the automobile is opposite, the impact the automobile gets will not be increased and the body will move in the manner that the front body goes up and the rear body goes down; moreover, when four wheels are not in a same surface or a pair of diagonal wheels bears a bigger force, the body and frame will get a certain amount of torque force; therefore, the current suspension structure still have the following pitfalls, e.g., elastic components are likely subject to be broken, the body and frame is likely subject to be distorted, and so on. In addition, articles carried in vehicles might be damaged and the passengers will feel uncomfortable.